This is a breaking change.
This commit changes the meaning of the `format` route attribute when
used on non-payload carrying requests (GET, HEAD, CONNECT, TRACE, and
OPTIONS) so that it matches against the preferred media type in the
`Accept` header of the request. The preferred media type is computed
according to the HTTP 1.1 RFC, barring a few specificty rules to come.
This commit includes the following additions:
* A `session` example was added.
* `Config::take_session_key` was removed.
* If a `session_key` is not supplied, one is automatically generated.
* The `Session` type implements signed, encrypted sessions.
* A `Session` can be retrieved via its request guard.
A few interesting notes on this breakage:
* `Cookie` how has a lifetime. It should be `'static'` everywhere.
* The `SetCookie` header is no longer reexported.
* Instead, `Cookie` implements `Into<Header>` for Set-Cookie.
This is a complete rework of `Responder`s and of the http backend in
general. This gets Rocket one step closer to HTTP library independence,
enabling many future features such as transparent async I/O, automatic
HEAD request parsing, pre/post hooks, and more.
Summary of changes:
* `Responder::response` no longer takes in `FreshHyperResponse`.
Instead, it returns a new `Response` type.
* The new `Response` type now encapsulates a full HTTP response. As a
result, `Responder`s now return it.
* The `Handler` type now returns an `Outcome` directly.
* The `ErrorHandler` returns a `Result`. It can no longer forward,
which made no sense previously.
* `Stream` accepts a chunked size parameter.
* `StatusCode` removed in favor of new `Status` type.
* `ContentType` significantly modified.
* New, lightweight `Header` type that plays nicely with `Response`.